历史上的一次溃决洪水--1482年沁河流域大洪水

据沁河流域九女台洪水题刻水位及相关历史文献记载,沁河流域1482年洪水洪峰流量极大,历时甚长,与该流域一般洪水过程的差异迥然.通过地貌调查,并利用14C测年等方法,对沁河九女台河段进行了详细研究,发现其1482年高洪水位是梯沟口泥石流-崩塌堆积物堰塞沁河主河道的结果.当年由于降雨,使梯沟流域发生泥石流,并导致沟口右岸岩壁崩塌,形成堰塞坝,造成沁河河道阻塞,过水断面减小,九女台附近河段水位壅高,并保持了近40天的时间,堰塞坝最终溃决,导致沁河下游怀庆府发生严重的洪水灾害.     

Phreatophytic Vegetation and Groundwater Fluctuations: A Review of Current Research and Application of Ecosystem Response Modeling with an Emphasis on Great Basin Vegetation

Although changes in depth to groundwater occur naturally, anthropogenic alterations may exacerbate these fluctuations and, thus, affect vegetation reliant on groundwater. These effects include changes in physiology, structure, and community dynamics, particularly in arid regions where groundwater can be an important water source for many plants. To properly manage ecosystems subject to changes in depth to groundwater, plant responses to both rising and falling groundwater tables must be understood. However, most research has focused exclusively on riparian ecosystems, ignoring regions where groundwater is available to a wider range of species. Here, we review responses of riparian and other species to changes in groundwater levels in arid environments. Although decreasing water tables often result in plant water stress and reduced live biomass, the converse is not necessarily true for rising water tables. Initially, rising water tables kill flooded roots because most species cannot tolerate the associated low oxygen levels. Thus, flooded plants can also experience water stress. Ultimately, individual species responses to either scenario depend on drought and flooding tolerance and the change in root system size and water uptake capacity. However, additional environmental and biological factors can play important roles in the severity of vegetation response to altered groundwater tables. Using the reviewed information, we created two conceptual models to highlight vegetation dynamics in areas with groundwater fluctuations. These models use flow charts to identify key vegetation and ecosystem properties and their responses to changes in groundwater tables to predict community responses. We then incorporated key concepts from these models into EDYS, a comprehensive ecosystem model, to highlight the potential complexity of predicting community change under different fluctuating groundwater scenarios. Such models provide a valuable tool for managing vegetation and groundwater use in areas where groundwater is important to both plants and humans, particularly in the context of climate change.     

关于中国塔里木河流域若干问题的辨识

塔里木河流域的水量及水质变化 ,生态环境质量的优劣 ,生态需水量的估算、整治目标的确定等问题 ,一直是该流域资源环境和社会经济的核心问题。对其近 40年来水文观测资料的时间序列进行分析 ,三源流区的水资源量逐年递增 2× 1 0 7m3,但干流上游阿拉尔来水量每年递减 3× 1 0 7m3。水质的劣变特征亦较明显。通过构建生态脆弱性指数 ,定量评价流域生态环境质量表明 ,干流下游已属于生态环境严重受损区。用潜水蒸发和定额法的原理估算植被耗水 ,提出了维护干流区生态环境在不同目标年的生态需水量。认为应当在水资源承载力和环境容量的阈限内 ,合理确定科学的保护方案     

关中盆地地-气系统灾变的节律性及耦合关系

依据丰富而系统的历史资料，建立了关中盆地历史地震与旱涝灾害两个数据库，分析了近2000a来地-气系统环境灾变的节律性及耦合关系。结果发现：(1)地震活动具有一定的节律性，并先后经历了3个平静期和3个活跃期，平静期与活跃期呈交替出现，具有3～4个世纪的周期；(2)较为严重的干旱、洪涝灾害亦具有一定的周期性，先后经历了2个洪涝期和3个干旱期，其较长尺度的转换周期亦为3～4个世纪；(3)在世纪尺度上，地震活动与旱涝灾害具有某种耦合关系，表现为在地震活动的活跃期，旱涝灾害呈多发性，而在地震活动的平静期，旱涝灾害较为稀少；(4)以较大级别的地震群发为节点，地气系统环境灾变的耦合关系具有先旱→后震→再涝的演替特征。基于上述事实，提出了一个地-气系统环境灾变的概念模型，对地震与旱涝灾害的耦合关系给出了确定性解释。为关中盆地世纪尺度的环境灾变群发性预测提供了新的依据。     

珠江流域人群对典型EDCs的暴露及致癌风险评价

研究以珠江流域为例,结合美国EPA致癌风险评估模型,通过构建多介质-多途径暴露模型,定量评估了该区域居民暴露于镉(Cd)、滴滴涕(DDT)和多氯联苯(PCBs)等典型EDCs污染物的致癌风险,分析风险来源、暴露介质及暴露途径,并探讨不同环境介质的致癌风险贡献率.结果表明:Cd、DDT和PCBs的暴露剂量达2.36×10-4,6.46×10-5,4.62×10-5mg/(kg·d);暴露途径中经口摄入是最主要途径;总致癌风险为2.04×10-4,高于国内外所规定的可接受致癌风险水平上限(1×10-4),环境介质中蔬菜和大米对致癌风险贡献较大,区域主要典型EDCs污染物Cd和PCBs对致癌风险贡献率较大(分别达44%、45%).     

长江流域生态环境协同规制的立法诠释与意涵表达——以《长江保护法》为述评视角

为解决长江流域生态环境治理模式中“权力—权利”主体间存在的结构性冲突,《长江保护法》以专门立法的形式对流域生态环境法律体系进行了统合性建构,创设出“环境公权机关统筹主导+环境私权主体竞相参与”的长江流域生态环境协同规制的新模式。该模式的塑造既有对构建我国现代环境治理体系这一顶层设计的积极遵循,也适配于社会性规制力量蓬勃发展的客观趋向,符合“成本—效益分析”视野下流域生态环境治理成本最小化的价值追求。以对长江流域生态环境治理法律秩序的高度统摄为依归,长江流域生态环境协同规制模式一方面沿循从“宏观宣示”到“微观赋权”的渐进性立法表达路径,对国家权力统筹主导流域治理的地位进行了立法诠释;另一方面也对社会力量多元参与流域治理的功能配置与职责序构作了妥善且周延的法律安排。在学理上,可从形式、理念与要素三重维度内容出发,对长江流域生态环境协同规制模式的法律意涵予以明晰。     

南渡江农业土壤中农药分布特征与生态风险评估

为摸清稻菜轮作土壤中农药(CUPs)残留特征与生态风险,采集海南岛南渡江流域稻菜轮作系统168个土壤样品,利用QuEChERS-超高效液相色谱-串联质谱(UPLC-MS/MS)检测土壤中25种CUPs残留水平,结合土壤因子与作物类型分析CUPs残留关键影响因素,以风险熵法评估其生态风险.结果表明,∑25 CUPs处于0...     

Temporal variations of CO2 concentration near land surface and its response to meteorological variables in Heihe River Basin, northwest China

Atmospheric CO2 concentration (CC) near land surface and meteorological variables have been measured at four sites,named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge) and Ejina (lower desert),respectively, in Heihe River Basin, northwest China. The results showed that, the half hourly CC at night was larger than in daytime,and the daily averaged CC was the largest in winter. The averaged CC of 932 d at the Linze was about 418 ppm, was about 366 ppm in the 762 d at the Ejina. In the same period from September 23 to November 9, 2004, the averaged CC was about 625,334, 436 and 353 ppm, at Yeniugou, Xishui, Linze and Ejina, respectively. The linear relationship between daily averaged CC and air temperature T was negative, between CC and relative humidity (RH) was positive. The linear CC-atmospheric pressure (A P) relationship was negative at the Linze and Yeniugou, was positive at the Ejina. The relationship between CC and global radiation R was exponent, and soil temperature Ts was negative linear, and soil water content was complex. The correlation between CC and wind speed was not existent.Using meteorological variables together to simulate CC, could give good results.     

黄河流域区域发展优势与经济带生成可能

基于进化经济学和进化经济地理学的理论,文章重点讨论了黄河流域的区域发展优势和建成黄河流域经济带的可能性。研究从黄河流域发展的历史出发,论证了黄河流域经济发展的区域地理学本性(nature)条件和现实可能性:第一,黄河流域经济发展的区域地理学本性条件是,该区域已经完成了农业经济建设,出现了遍在性的工业化和经济区人口聚集,特别是经过长期聚集,黄河流域已经形成了中国的人口密集带,形成了具有区域发展优势的中原城市群。第二,在分析黄河流域区域发展优势基础上,提出建成“大中原-黄河经济带”的可能性及其发展途径,即在生态保护的前提下,坚持地理环境的鲁棒性建设,坚持城市创新发展,坚持发展新型产业。第三,地区发展政策重点应该关注中原城市群的工业化-城市化发育和一体化产业链的形成,根据新经济地理学理论,提倡城市产业专业化方向,打破省界限制,发挥经济区的地缘结构优势,在空间上与环渤海经济带融合,完成黄河流域经济带高质量发展的战略构想。     

海河流域植物中碳的输出(或存留)量和土壤中的库存量

研究了海河流域地区植物中碳的输出量和土壤库存量。结果指出：不同作物－土壤系统中各种作物碳的输出量和归还量有很大不同,作物碳输出量一般为归还量的３－１７倍;海河流域地区不同子流域土壤中碳的库存量也有差异,以滹沱河子流域土壤碳的库存量最高,大清河子流域土壤中碳的库存量最低。